Area Forecast Discussion
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000 FXUS61 KPBZ 300734 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 334 AM EDT THU OCT 30 2014 .SYNOPSIS... BUILDING HIGH PRESSURE TODAY WITH DRIER WEATHER. ANOTHER LOW PRESSURE SYSTEM WILL BRING UNSETTLED WEATHER FRIDAY AND SATURDAY. && .NEAR TERM /THROUGH TONIGHT/...
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NEAR SFC FLOW VEERED NWRLY OVERNIGHT AND A PLUME OF LAKE MOISTURE DEVELOPED LOW STRATOCU OVER THE SRN SHORES OF LAKE ERIE AND AREAS ADJACENT. SRN EXPANSION OF THIS CLOUD COVER HAS NOT BEEN NEARLY AS AGGRESSIVE AS PREVIOUSLY FORECAST...HOWEVER...AS DRY AIR ALOFT HAS BEEN ABLE TO ERODE THE MOISTURE UNDER THE UPPER TROF AXIS. THIS HAS SQUASHED WIDESPREAD LAKE-INDUCED SHOWERS AND HAS LED TO ALMOST THE SRN HALF OF THE CWA REMAINING CLEAR THROUGH THE PRE- DAWN HOURS. WINDS HAVE GENERALLY STAYED UP OVERNIGHT ALLOWING SOME MIXING OF THE LOW LEVELS...BUT SHELTERED LOCATIONS UNDER CLEAR SKIES HAVE RADIATED DOWN INTO THE MID 30S. LOOKING FORWARD...CLOUD FORECAST DIFFICULT THROUGH TODAY AS MOST HI-RES MODELS HAVE NOT FULLY RESOLVED THE EXTENT OF THE DRY AIR INHIBITING CLOUD DEVELOPMENT IN THE LOW LEVELS. MODIFIED THE INITIAL SKY FORECAST BASED ON CURRENT SATELLITE TRENDS AND HAVE GRADUALLY BLENDED INTO TONED DOWN VERSION OF THE PREVIOUS FORECAST. EXPECTING TO SEE MOSTLY CLOUDY CONDITIONS PERSIST ALONG THE NORTH UNDER THE LAKE ENHANCED REGION WHILE GETTING AT LEAST SOME PATCHES OF SUN FURTHER SOUTH IN THE CWA. FORECAST AREA REMAINS COOL TODAY UNDER NW FLOW REGIME. WITH VERY LOW SPREAD ACROSS GUIDANCE FOR TEMPS...HAVE MAINTAIN CURRENT FORECAST WITH MINOR TWEAKS BASED ON BIAS CORRECTED MET. TAX
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY/... SFC HIGH PRES IS EXPD TO BLD IN UNDER BROAD UPR TROFG THU. THE UPR TROF IS EXPD TO DEEPEN BY FRI AS AN ASSOCIATED SFC LOW AND CDFNT ADVN ACRS THE RGN. THE DEEPENING TROF IS PROGGED TO DVLP INTO A CLOSED LOW OVR THE OH VLY FRI NGT...MOVING OFF THE CAROLINA COAST BY LT SAT. MOISTURE AND OMEGA ON THE NRN SIDE OF THE LOW IS EXPD TO KEEP PCPN ACRS THE RGN INTO SAT. CRITICAL THICKNESSES AND SOUNDING PROFILES INDICATE A RAIN/SNOW SHWR MIX BY FRI NGT INTO SAT...OR EVEN A CHG OVR TO ALL SNW ESP IN THE RIDGES SE OF PIT. SOME LGT ACCUMS ARE PSBL MAINLY IN THE COLDER HIGHER TERRAIN LOCATIONS...THOUGH VRY LTL UPSLOPE FLOW COMPONENT IS EXPD WITH N-NNE WNDS SAT. PCPN CHCS SHOULD BE DCRG LTR SAT AS THE UPR LOW BEGINS TO EXIT OFF THE COAST. TEMPS SHOULD AVG 5-10 DEG BLO SEASONAL LVLS LT THIS WK...AND ARND 15 DEG BLO SEASONAL LVLS SAT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... WPC SUGGESTS FOLLOWING ENSEMBLE MEANS IN THIS ANOMALOUS PATTERN AND SEE NO REASON TO DISAGREE. HIGH PRESSURE WILL BUILD IN BEHIND THE DEPARTING DEEP SYSTEM. WITH THE NORTHEAST TROUGH HANGING AROUND THROUGH THE WEEKEND...TEMPERATURES WILL CONTINUE TO RUN WELL BELOW NORMAL. SATURDAY NIGHT MAY BE THE COLDEST OF THE SEASON THUS FAR WITH WIDESPREAD READINGS IN THE 20S. MODERATION CAN BE EXPECTED FOR MONDAY AND TUESDAY AS RIDGING DEVELOPS ONCE AGAIN. THE NEXT FRONT MAY ARRIVE COME TUESDAY NIGHT OR WEDNESDAY WITH RAIN SHOWER CHANCES. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... GENERAL VFR FORECAST THROUGH THE DAY FOR MOST LOCATIONS...ALTHOUGH MVFR CIGS COULD BE OBSERVED TEMPORARILY THIS MORNING AS LARGE STRATO CU FIELD DESCENDS FOLLOWING A PLUME OF LLVL MOISTURE FROM LAKE ERIE. FKL AND DUJ WILL STAY MVFR THROUGH LATE MORNING BEFORE IMPROVING LATER IN THE AFTERNOON COLDER AIR WILL SLOWLY LIFT NORTHWARD THURSDAY ALLOWING FOR STRATOCU DECK TO EVENTUALLY THIN OUT. OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/... WIDESPREAD RESTRICTIONS ARE EXPECTED ON FRIDAY AS DEEPENING LOW PRES IS PROJECTED TO SHUNT A BROAD MSTR SWATH OVR THE UPR OH REGION. ENSUING COLD ADVCTN WL THEN MAINTAIN STRATOCU POTENTIAL UNTIL SFC HIGH STRENGTHENS ON SUNDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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